Lecture #13

Question 1

epigenetics

Answer 1

the study of environmental factors that change phenotype by changing gene expression without changing the gene sequence

Question 2

turning genes on/off

Answer 2

-genome is very tightly packed into chromosomes -to turn on/off a gene, the chromosome has to be opened up and closed back down

Question 3

gene sequences

Answer 3

-changing the pattern of expression of the same genes gives different genotypes

Question 4

hox genes

Answer 4

-controls where you make the different segments of your body -same in human and fruit fly

Question 5

epigenetic modifications

Answer 5

-heritable cellular states that can alter the output of the genome -usually refers to biochemical groups that modify the structure of chromatin

Question 6

Are genetically identical twins always the same?

Answer 6

no bc epigenetics

Question 7

two major biochemical groups for epigenetics

Answer 7

1. methyl (-CH3) 2. acetyl (-C=OCH3) act as on and off switches

Question 8

methyl groups

Answer 8

-usually act as off switches -usually bind at CpG islands -controlled by DNA methyltransferases -added to the C and creates a bulky group so that the transcription factor can’t bind anymore and won’t turn on that gene

Question 9

acetyl groups

Answer 9

-usually act as on switches -bind on histones (around which, DNA is wound) and are controlled by histone acetylases -bound less tightly bc it’s in the way, easier for the transcription factor to get in there, turns it on

Question 10

What compound is this?

Answer 10

vinclozolin -fungicide used on wine grapes -causes sperm count reduction in F3 generation

Question 11

Why do we care about epigenetics?

Answer 11

many environmental chemicals can affect levels of methylation and acetylation

Question 12

Why do organisms have epigenetics?

Answer 12

-allows the same genome to do different jobs -allows intermediate timescale adaptations (beyond physiological changes and evolution)

Question 13

difference between worker and queen bees

Answer 13

-fundamentally different organisms -caused by royal jelly –> silences DNA methyltransferase –> less methylation –> less off switches

Question 14

BPA epigenetics

Answer 14

-when treated with soap/heated, monomers escape -potentially causes childhood obesity -can hypomethylate DNA

Question 15

agouti mouse model

Answer 15

-thin agouti mouse + fat yellow mouse

Question 16

What compound is this?

Answer 16

genistein -hypermethylates DNA -found in soybeans